I have a 1988 F-250 with a 351W C-6 auto with 4:10 ratio rear and a crane powermax cam 252/260 adv dur .416/.432 gross lift rpm range 800-4200. The truck has shortie headers real dual exhaust. I just purchased a set of GT-40 heads is it worth the swap. I want a torque monster. The truck cant spin the tires? stock size. Is it worth the head swap? And should I change to MassAir with a bigger cam? stroker I need help.....

 

With both you'll need to go to mass air. You're probably running lean now with the cam change.

 

whats the lob seperation on that cam? that truck is still efi right? How many miles on the motor and tranny? the C6 is a major performance hog until its rebuilt properly with some aftermarket goodies.

 

That cam is pretty much a stock replacement, the motor could use lots more, and the shorties are not helping TQ production at all, get longtubes. The GT-40s may help TQ if the combustion chamber is smaller, compression ratio on the early 5.8's is down around 8.5:1. Mass air will allow much more timing advance as well as other benefits. My 5.8 has no problem spinning both tires on dry pavement...

 

the C-6 has a shift kit and was rebuild with the motor they both have around10K on them. Is it worth extrude honing the lower and upper intake for better breathing and what about Ma-air whats the best one to convert over? The GT-40 heads have 60-63 cc chamber size and 1.84"Intake and 1.54 exh. If I do build a stroker is the intake going to choke the motor? a 426 or a 408? First I want to get the most out of the 351 what else can I do besides extrude the intakes and the head swap?

 

yes its still EFI..

 

what is that cams lob seperation? that could be causing some of your problem. building a torque motor that intake will probably be fine as will those heads. a mass air swap will be necessary though. check out this site for a plug and play harness.
http://www.flowmanagementunlimited.com

Or i have some mass air stuff like wiring and ecu if your interested, just pm me

 

Forget hogging out the intake, bigger runners decrease TQ, not the other way around. The motor is strangled by the cam, get a Comp Cams 35-255-5 in there and longtubes.
If you build a stroker, the stock intake is no good at all. Hell.. if you want more than 250hp on the 351 the stock intake is too small. But you want a "torque monster", so HP should not matter.

 

how is your set up? With that cam do I need to convert to Ma-Air. what about a torque converter?

 

My complete setup is SD friendly, The Crane 444232 was an upgrade for the stock Lightning which was SD. I have the mass air kit because back when I did the 5.0-5.8 swap I was told it was necessary, I know othewise now. If you are starting out with a 5.8 truck then there is absolutley no need to touch the computer until you outgrow the 19lb injectors, which is near the 300hp mark. To get beyond that you'll need a different intake and heavily ported or aftermarket heads, so that's when things get real expensive.
This truck operates like a stock vehicle, starts easily and idles smoothly. But it has tons of low rpm torque.. no problem to powerslide around corners on many city streets just by punching it while rolling.. it's got a tight LS diff as well. It's a bit difficult to drive on wet streets actually, have to feather the throttle off stops and take it easy around corners or it just breaks em loose!! It's also pretty amazing the hills it will climb at HWY speeds in OD without loosing any speed.

I don't like torque conveters in street vehicles, especially something that will be used as a tow rig or if you expect to get reasonable milage. Also, if you have the right gearing for the engine powerband and vehicle weight then the converter is not needed. Others may disagree.. but hey.. that's my take.

 

what size tires r u running and what gears???